Inflatable underwater structure

ABSTRACT

An inflatable underwater structure for providing an artificial environment around a work area, for example, at the sub-sea base of an off-shore oil platform, permitting such work as welding and the like; the structure is made up of one integral sheet of material for a custom job or a series of selected sheets fastened together about the structural support members; the material includes zippered sections so that the material can be placed about and around the structural members; in order to insure a substantially air-tight system, neck sealing means are included about the structural members at their intersection with the sheet material as well as air-tight means within the zippered sections; although the system could be used on land, it is particularly applicable to sub-sea situations.

United States Patent 9 1 Scurlock Sept. 24, 1974 [54] INFLATABLE UNDERWATER STRUCTURE 3,475,915 11/1969 Caplan 61/69 R Inventor: J T. Scurlock 6209 Schovest, 3,496,730 2/l970 TSUJI 61/69 R Metame 70003 Primary Examiner-J. Karl Bell [22] Filed: Apr. 10, 1973 Attorney, Agent, or Firm-Pugh & Laiche 21 A I. No.: 349 709 1 pp R 57 ABSTRACT elated Application Data An inflatable underwater structure for providing an [63] Commuatw F- 1971' artificial environment around a work area, for examabandoned, wind] is a continuation-impart of Ser. ple at the sub sea base of an offlshore Oil platform, 843S43JuIY 1969 abandoned permitting such work as welding and the like; the structure is made up of one integral sheet of material [52] US. Cl. 61/69 R, 52/2 for a custom job or a Series of Selected Sheets fastened [51] Int. Cl. B63c 11/36, E04b 1/343 to ether about the Structural su port members, the [58] Field of Search ..61/69, 63, 46; 114/16; l d d p th h t l 35 nu ma ena mc u es zlppere sections so at t e ma erial can be placed about and around the structural members; in order to insure a substantially air-tight [56] 1 References Clted" system, neck sealing means are included about the UNITED STATES PATENTS structural members at their intersection with the sheet 3,332,176 1967 Knetler 52/2 material as well as air-tight means within the zippered 3,335,529 8/ 1967 Gedney 52/2 sections; although the system could be used on land, it 3386354 6/ cmnany 61/69 R is particularly applicable to sub-sea situations. 3,452,764 7/l969 Bell 135/1 R 3,456,403 7/1969 Batterson 52/2 18 Claims, 29 Drawing Figures PAIENIEBSEPZMW 'mvsmozz JOHN T. SCURLOCK ATTORNEY I BY PAlimmstPzmu saw 2 ar e FIG.2A.

INVENTOR. JOHN T. SCURLOCK BY 6 ATTORNEY PAIENIEDSEPMHH mint! 6 I I INVENTOR.

- l2 JOHN T. SCURLOCK 7 BY 6. WW I ATTORNEY pglgmnwzwu am at s FIG; l2.

iNVENTOR. f 7 JOHN T. SCURLOCK I 'ATTORNEY Pmmwz smears mvsmon JOHN T. 5%OCK BY {ma w w w G 3 .2 v v F FIG. 22.

ATTORNEY REFERENCE TO RELATED APPLICATION This application is a continuation of my copending application Ser. No. II2,86I, entitled Inflatable Underwater Structure and 'filed Feb. 5, 1971, now abandoned, which is a continuation-impart of my copending US. application Ser. No. 843,543, entitled Air Wrap Product and filed July 22, 1969 now abandoned.

BACKGROUND OF THE INVENTION This invention relates in general to the providing of an inflatable underwater structure about one or more steel Structural members which can be used to create a sub-sea artificial enviroment around a work area to easily and safely permit suchwork activities as inspection, welding, x-raying and painting.

-- A very serious problem which has been facing the off-shore oil industry is the great difficulties involved in properly maintaining and repairing the subsea steel structural support members in off-shore platforms and in the various submarine pipeline systems. A particularly acute problem has been in trying to weld in a subsea enviroment.

' In attempting to overcome these problems the prior art has tried to use steel diving and welding chambers in order to create an artificial enviroment or atmosphere for sub-sea work. However, such chambers are ino'rdinantly expensive and clumsy to use. Moreover, when the work has to be done in an area where there are several s'teel structural members radiating out at different angles, the diving chambers could not be used or else, if used, often caused more damage to the associated production tubes or risers or to the secondary structural members than originally existed on the membet to be repaired.

'Alternately, welding techniques have been devised for welding directly in the wet enviroment but these techniques have been unsatisfactory and highly dangerous and usually produceda high percentage of inferior weldments. I

.T he present invention overcomes the problems of the prior art by providing an inflatable underwater structure which can be used regardless of the structural complexity of the work area to create an artificial, gaseous enviroment such as air around the sub-sea work area. As will be seen more fully below, the inflatable structure is relatively inexpensive, takes no esoteric skills to assemble, other than certain basic training, and allows for the ideal enviroment within which the work may be performed. Thus, .with air in the inflatable structure a worker need not use the relatively clumsy scuba diving equipment while he is at work.

The inflatable structure can be broken down as de-' sired for easy portability and because of its relative inexpensiveness can be stocked atmany locations in the field to allow for immediate use.

These and other great advantages and objects of the present invention over the prior art will become apparent in the description and discussion of the details of the'preferred embodiments presented below.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a perspective view of the assembled, inflated structure of the present invention, partially cutaway, showing the workman in the interior of the structure;

FIG. 1B is apartial top view of the inflated structure;

FIG. 2A is a partial, perspective view of the neck interface between the inflated structure and a structural member, while FIGS. 28 and 2C are top and side crosssectional views, respectively, of the neck interface;

FIG. 3 is a side,,cross-sectional view, similar in perspective to FIG. 2C, of a second embodiment of the steel outer band clamp for the neck interface;

FIG. 4 is a partial, cross-sectional view of the material of the inflated structure showing the zipper details of the material;

FIGS. 5 Aa'nd B, and 6 are partial, cross-sectional views, similar in'perspective to FIG. 4, showing second and third embodiments, respectively, of the water-tight portions of the zipper elements;

FIGS.;7, 8 and 9 are perspective views of three types of sections of the inflated structure, viz., sections in which there are no structural cross-members, one structural cross-member and two 'structural crossmember s, respectively; b I

FIG. 10 is a partial, cross-sectional view of the various layers of material used in the inflatable structure of the present invention;

FIGS. -'15 are perspective views of the various steps followed in assembling and inflating the inflated structure of the present invention;

FIGS. 16 23 illustrate various accessories used in association with the inflated structure of the present invention; more particularly: I

FIG. 16 isa partial, cross-sectional view of the material of the inflated structure showing the stress points and D-rin'gs FIG. 17 is a perspective view of one section of the structure showing the relative locations of the flotation pockets and the snap-on weights;

FIGS. 18A and B are perspective and cross-sectional views, respectively, of two types of sealing members for sealing off fractures within the steel structural members being worke'don;

FIGS. 19 A and B are side, perspective and top, cross-sectional views,respectively, of a structural support member with a riser tube next to it, illustrating the use of hot dog tubes to make a rounded structure;

FIG. 20 is a top, cross-sectional view of a channel beam, using fhot dog" tubes to produce a rounded surface;

FIG. 21 is a partial, cross-sectional view showing the teeth-like" projections on the internal side of a stress clamp used with the present invention;

FIG. 22 is a perspective view on the inside of the inflated structure showing a floating platform accessory is use; and

FIG. 23 is a perspective view on the inside of the inflated structure showing the placement of a welding hood accessory.

As illustrated in FIG. 1A, the present invention provides an inflatable structure 1 for creating an artificial enviroment 2 such as air about a work area 3 at a subsea level.

The construction material of the air bag 1 of the present invention is designed in such a way that it is adaptable to whatever complex contours or configurations which the structure members surrounding a work area may present. However, for the purposes of illustration, the specific embodiments herein will be described as applied to a typical support structure of an off-shore platform having a vertical support member and one or more cross-members or braces emanting from the support member. Thus, the inflatable structure 1 is made of flexible film material and is adapted to be fitted about and around the structural support member 4 and structural cross-members 5, 6 and 7 which are to be worked upon.

As will be explained more fully below, the structure 1, when inflated provides in effect an open-bottom, multi-section, air filled balloon in which a diver 8 can freely work below the water surface. The diver 8 suspended on, for example, sling 9 can thus inspect, weld, x-ray, paint or do any other desired work in the artifical, controlled atmosphere provided within the substantially air-tight and water-tight inflated structure 1.

In order to permit universal application, i.e., application to many different'structural configurations, the

air bag 1 is made up of a multitude of various sections, each designed for a particular type of application. Thus for the support structure of FIG. 1, the air bag 1 includes four sections 10 13, which are interconnected together by means of water-tight zippers 14 along their side peripheries.

Bag sections 10 and 11 include no opening (note FIG. 7), while section 12 includes two openings for the cross-members or braces 5 and 7 (note FIG. 9). Bag section 13 includes one opening for cross-member or brace 7 (note FIG. 8). Alternately, in place of section 13 one could use a two-opening section like section 12 by tying off and completely closing the unused or unnecessary opening. Additionally other types and forms of sections for other applications can be provided. Each section is typically 25 inches across at its upper end and I00 inches across at its lower end.

In order to produce a water-tight seal between the bag material 15 and the particular structural member 16 to which it is attached, a neck interfacing portion is provided. As illustrated in FIGS. 2A C, the neck portion 17 includes a layer of air bag material 15 placed next to the structural member 16 and on top of which is placed a layer of foam material 18. Foam materials forthe layer 18 have been found to be a low density closed cell foam or a non-connected cellular foam such as a polyvinylcholride resin based foam. Such foam layers are watemight. The foam layer 18 can include a to be normally avoided of course is the uncontrolled leakage of the air.

Alternately, it has been found that, rather than the standard flat steel band clamp 19, superior sealing results can be obtained by using a ridged-surfacedouter clamp such as that illustrated in FIG. 3.. The alternate, outer clamp 20 is likewise made of a flexible,ban d. material but includes on its bearing surface two pr1ntore ridges 21 (two illustrated) running a et: its l ength.

To complete the air/water tightness jof theinflated structure 1, it is necessary that the zippers 14 likewise possess a substantial degree of air/water tightness. There is available in the market several brands of water-tight zippers and these may beused for the zippers 14. However, because of the relatively delicate nature of these standard, prior art zippers, it is necessary to isolate these zippers from any substantial stress or strain.

This isolation may be accomplished by structuring the inflatable material in the manner shown in FIG. 4.

To provide this isolation, the inflatable material 22has an inner lining 23 of air and water impervious film material and an outer layer 24 of strong material such as coated nylon. The outer layer is designed to absorb and withstand all the stresses and strains placed on the inflatable structure and includes a strong, heavy duty structural type zipper 25 which is not necessarily watertight but can withstand high stress without failure. The inner lining 23 includes a water-tight zipper 26 on which not structural stresses are placed because of the presence of slack sections 27 included in the film material 23. Thus by using two zippers; one for structural strength and the other for water-tightness, a workable solution is achieved.

However, in spite of the general isolation-bf watertight zipper 26 from stresses, field tests have shown that on occasion undue stress is still placed on thezwater tight zipper 26, particularly during the assembly of. the bag structure 1 causing it to fail. Hence a totally new zipper structure, avoiding completely the use of delicate water-tight zippers, has been devised and two embodiments of this new sealing structure are illustrated in FIGS. 5 and 6. v

The first embodiment 14' (FIGS. 5A and B) of this new water-tight zippered structure for the material 28/28 of the inflatable structure includes a two-part housing 29/29 joined together by two heavy-duty structural type zippers 30/30. Included within the housing 29/29', which is made of water impervious material, is an elongated inflatable bag 31 and water-tight sealing means 32 34. Sealing means 32 '34 comprises a layer 32 of water impervious material extend ing out from the wall 29 of the housing and having a section 33 of low density closed cellular foam at its other end. On the surface of the housing wall 29 opposite to the foam section 33 is a projecting, longitudinal bead 34. The, bag 31, layer 32 with foam section 33,.

and the bead 34 extend the full length of the outer housing 29/29.

In order to interconnect the material sections 28/28' and effect a water-tight seal therebetween, the two zippers 30 30' are zippered closed and the internal bag 31 inflated. As the bag 31 becomes inflated, it expands out against the layer 32 which in turn is pushed toward and against the bead 34 (note direction arrows in FIG. 5A) until it reaches its fully inflated state (note FIG. 5B).

In order for air or water to leak from one side of fabric material 28/28 to the other side, it must pass through the two zippers 30, 30 via the intersection of the foam section 33 and the longitudinal bead 34, as

well as between the mating surfaces of the wall of the bag 31 and the housing wall 29. However, the sealing means 32 34 is highly effective and no substantial leakage occurs.

In order to increase the sealing effects of the zippered structure, a second embodiment 14" (FIG. 6) is illustrated, similar in structure to the first embodiment 14' but having a multiple number of sealing layers. Like numerals are used for the same elements and they all function as described above with respect to FIG. 5. The zippered structure 14" of FIG. 6 includes a multiple number of layers 32, 39 41 of water impervious material alternately extending out from the housing walls 29/29. Alternately foam sections 33, 36, 38 and longitudinal beads 34, 35, 37 are provided to form .a series of water sealing intersections or surfaces as the bag 31 v is inflated, these sealing intersections, all of which must be traversed before leakage occurs, completely seal off the zippered structure 14''.

Many variations of these water-tight, zippered structures are possible, the only basic thing required being of course that some water sealing, mechanical means be provided in the path between the two zippers 30, 30'. Likewise the precise material used for the fabric of the inflatable structure or air bag is somewhat optional as long as it is flexible, easy to handle, light-weight and water impervious.

A material that has been found satisfactory has been a composite material made up of the following layers (as generally illustrated in FIG.

a. an inner layer or interliner 42 of abestos coated material for resisting heat and fire;

' b. a film layer 43 that is 100% water-tight and is of inflatable quality throughout the entire enclosure;

0. a coated, nylon layer 44 that has the desirable strain capabilities such that it will have sufficient strength under most presurable working conditions; and

d. a second, coated nylon layer 45 for the exterior layer to resist the excessive abrasive conditions which must be faced in use.

The bag material may consist of all of the above or only a partial number of the above layers or a duplication of the layers, depending upon the requirements of a particular job. The layers can be interconnected by flanges 46 (illustrated in their untaut condition) or the like or the layers and sections of the material can be rejoined together by sewing, electronic welding orzusing adhesives.

The over-all bag material of course is fabricated in such a manner that the scams or perimeters of the material must have some form of closure (zipper or otherwise) that will have both the requisite strength and air/- watertightness when used to join two pieces of the material together. Appropriate neck interface portions for mating with and allowing for the penetration of crossmembers must also of course be provided for.

Moreover, rather than using the universal" multitype sections 10 13 to make up the inflatable bag, customized bags could be made for each particular job. Thus, if the bag and job site illustrated in FIG. 1 had been approached on a one-time use, customized basis,

three of the four full-length zippers 14 could have been eliminated, the bag being made from one continuous sheet Such a customized approach is practical because of the relative inexpensiveness and potentially great availablilty of the material used in the present invention.

Because of the relative vulnerability of the zippers, particularly the prior art water-tight zippers, it is desirable to have them isolated from as much lateral or surface stress as possible. In order to achieve this, stress belts 47 (note FIGS. 1 and 7 9) are included .across the zippers pulling the material together and taking up the lateral stress in those areas.

Alternately, an enclosing net 140 of mesh material, following the general configuration of the air bag but defining substantially less enclosed volume when fully extended than the air bag, is placed on the exterior of the air bag before inflation (note FIG. 14). When the bag is inflated, the outer net 140, having a less total maximum confined volume, prevents the bag from being expanded to its full extent (note FIG. 15). The net 140 thus prevents the creation of any substantial or damaging lateral or surface stresses on the zipper structure and absorbs the bulk of the stresses.

Of course, it may be desirable to provide a different gaseous enviroment other than air, for example,-in welding, certain inert gases surrounding the work area may be desirable. Indeed, it may in some cases be desirable to provide a liquid enviroment other than water for the work area and, as long as that liquid is substantially less dense than the surrounding water, such a liquid enviroment could be used.

The inflatable structure of the present invention is designed to have a great degree of flexibility and adaptability. In use various different needs may exist or unique problems arise, most if not all of which can be readily met and faced.

In particular, as generally illustrated in FIG. 16, various D-ring elements 120 are placed about the air bag material on both sides of the material. These elements can be used on the exterior to tie or weight down the material 105 or internally can be used to support underwater lights or other accessories. As discussed above, the bottom D-ring' elements 120 can be used to add on snap-on weights 108 during the initial assembly steps of the air wrap structure.

In some situations, the structural support members 106 or structural cross-members 113 themselves may be fractured around the work area, resulting in an undesirable air leak from the inflated air wrap structure. In such cases, secondary sealing means can be used to 'seal off these leaks. As shown in FIGS. 18A and B,

small fractures in the steel column or casing 106 can be sealed by means of appropriate foam sealing material 121 held against the fracture by means of magnetic flange element 122. For large or long fractures, a large or extended piece of foam sealing material 123 held to and around the casing by means of two steel band clamps could be used.

In some cases the structural support or crossmembers in the work area do not present a completely rounded surface to which the neck portions of the air wrap material can be attached. Examples of such situations are when a riser tube 125 is juxtaposed next to a support' member 126 .(FIGS.'19A and B) or when the structural member is not a pipe or cylindrical casing but rather an I-beam or channel beam 127 (FIG. 20).

In order to create a rounded surface in such situations,

relatively small, inflatable, hot dog shaped fil er bags 128 inflated to a high pressure are used. The hot dog" bags 128 are placed in and around the undesirable surface contours until a generally rounded surface is presented. Because of the pressure differential between that of the hot dog bags and the neck portions 111, 112 of the air wrap material when fastened about the structural members 125 126, 127 with the bags 128 added, the hot dog bags under the pressure of the neck portion will present a smoothly rounded surface making for a good interfacing seal between the two. As illustrated in FIGS. 19B and 20, when presenting this smoothly rounded surface, the cross-sections of the bags 128 will lose their own rounded shape and conform to the surfaces which they meet.

As shown in FIG. 21, the stress clamps 129 used against a metal surface may have on their inner surface, i.e. the surface bearing against the material being clamped, a series of teeth 130 to give a better grip to the clamp.

To enhance the use of the work area created within the inflated structure of the present invention various other accessories may be used. As illustrated in FIG. 22

v a floating working platform 131 can be provided. The

platform 131 floats on two pontoons 132 and is tied to the column 106 by means of support cables 133 and stress clamps 134. The platform could be further secured to the air wrap structure 105 by means of line 135 attached to an internal D-ring element.

Likewise, a welding hood 136 could be attached to the column 106 by means of support cables 137 connected to stress clamp 138 (note FIG. 23). An appropriate exhaust line 139 would lead from the top of the hood 136 down and outside of the air wrap structure 105 up to the surface.

METHOD OF INSTALLATION A method of installing the multi-sectioned inflatable structure of the present invention is as follows:

By the use of divers the area to be worked upon is surveyed and the dimensions and structural disposition and alignment of the work area are detailed. In accordance with the results of the survey, the appropriate sections to make up the inflated structure are selected and prepared.

As a precaution and to permit pre-assembly, it is desirable to make a mock-up of the work area on the surface and the sections pre-assembled on the mock-up or dummy rack to insure a good fit. After complete assembly on the mock-up one whole seamfrom top to bottom is unzippered and all neck interfaces and seams leading thereto are opened. The partially opened but interconnected sections of the material are then folded into a bundle 101 and tied to an anchor strap 102 which in turn is tied to a lowering cable 103 havinga weight 104 at its end. I

As illustrated in FIG. 11, the weighted cable 103 is then lowered into the water for preliminary connecting of the air bag material 105 to the support structure 106 in the area where the work is to be performed. As the air bag material 101/105 is'lowered, the air bag material 105-expands (mm FIG. 12) due to the flotation pockets 107 of styrofoam keeping the upper half up. The anchor strap 102 is tied to the air bag material 101/ I at approximately the middle of the material and supplemental, lowering weights 108 are attached to the bottom of the material 101/105. As a result, the air bag material 105 opens out with a vertical 'disposition comparable to its general disposition when installed.

After or as the air bag material 101/105 is' lowered to the desired position along side the work area, a diver descends to install the material. The diver attaches a temporary band 109, which can be a small stress band, to the vertical support column 106 and'also-to the middle of the air bag material 105 by means of line 110 (note FIG. 12).

As illustrated in FIG. 13, the air wrap material is then placed about the steel column 106 so that the'inte'rmediate neck portions 112 are aligned with their corresponding cross-members 113, and its upper end attached to the column by means of its neck interface portion 111 (note FIG. 13). The full seam 114 that was completely opened on the surface after the preassembly is then at least partially zippered closed.

The neck interface portions 112 are then secured about the cross-members 13 and clamped tight. The zippers 114 and 115 are then zippered completely closed.

A lower stress clamp 116 is then placed down below the air wrap material 105 on the support column 106 at the desired, pre-selected level. Tie down lines 117 are attached between the bottom of the material 105.

and the lower stress clamp 116' in order to hold down the air wrap structure 105 when inflated. Alternatively The on-site assembly of the basic inflatable structure is now complete and air or other appropriate gas is introduced by means of air hose 119 and the structure is inflated. Upon inflation, an artificial air enviroment is provided so that a worker can perform his work in air rather than in a wet enviroment regardless of sub-sea depth.

The inflatable air bag of the present invention, as well as being flexible in structural details, is also flexible in application. The air bag concept of the present invention, although particularly applicable to sub-sea work may also be applied to situations on land where a special enviroment or simple enclosure is needed.

Moreover, total submersion of the bag is not necessary for its operation in the marine field. Indeed, one particular useful application of the present invention is to the repair and maintenance work of off-shore installations at the water/air interface of the structure. Wave action on these structures causes a particularly severe corrossion problem. In such repair or maintenance work the air bag would be only partially below water, its lower extremity being submerged providing a seal while its upper extremity would be above water.

Although a particular structural application, i.e. a structure having a vertical column with several diverging arms, is illustrated herein for a description of the preferred embodiments, the invention is of course not so limited. The air bag can be easily adapted to practically any structure, whether horizontal, vertical, angular or a combination thereof. For example, the air bag can be used to repair or work on off-shore or sub-sea pipelines which lie on the ocean floor, basically a horizontal application, by arranging the neck opening at opposite sides and tying the bag down and under the pipeline.

As is readily apparent from the discussion above and the various exemplary alternatives, nearly unlimited variations, alterations and changes in the design and detail of the preferred embodiments and their applications are possible within the scope of this invention.

Because the invention is capable of many different embodiments and of being practiced and carried out in various ways, it should be understood that the invention is not limited in its application to the details and arrangement of parts illustrated in the accompanying drawings. It should also be understood that the phraseology or terminology employed herein is merely for the purpose of description and not of limitation, and the invention claimed herein is not to be limited beyond the requirements of the prior art.

What is claimed for invention is:

1. An inflatable, inverted bag-like enclosure structure of flexible material for fastening about and to a rigid structure, at least a part of which is in water, to define an enclosed work space, at least a portion of which is below the water, about said rigid structure, and having an internal, gaseous environment which supports by its pressure said enclosure structure, said internal environment being different from that on the outside of said enclosure structure, said enclosure structure compris ing a multiple number of separate but joinable extended sheet sections of flexible material, and joining means mounted at the edges of said sections for joining them together, said sections when joined together having at least one aperture therein, which is fitted around said rigid structure, and a relatively large bottom openmg.

2. The enclosure structure of claim 1 wherein there is further included sealing means along said aperture for at least substantially sealing said enclosure about said rigid structure.

3. The enclosure structure of claim 1 wherein said joining means comprises a zipper structure located along the periphery of said sections.

4. The enclosure structure of claim 3 wherein said joining means includes dual wall sections each joined together along their edges by means of zipper structures, one being a strong, heavy duty, structuraltype of zipper structure which can withstand high stress, and the other being a water-tight zipper structure, the later including slack portions in its wall sections, thereby avoiding any great structural stresses from being placed on said water-tight zipper structure.

5. The enclosure structure of claim 3 wherein said joining means includes two wall sections each joined together along their edges by means of zipper structures which define between themselves an enclosed housing, one of said wall sections including a flap layer of water-impervious material extending out therefrom within said housing and having sealing section means at its distal end for mating with the opposing part of the wall section from which it extends and for forming a water-tight seal between said flap layer and said opposing part, pressure means being included within said housing for pressing said sealing section means against said opposing part.

6. The enclosure structure of claim 5 wherein said pressure means comprises an inflatable bag.

7. The enclosure structure of claim 5 wherein there is included a projecting, longitudinal bead on said opposing part where it mates with said sealing section means for enhancing the sealing action.

8. The enclosure structure of claim 5 wherein said sealing section means comprises a section of low density closed cellular foam.

9. The enclosure structure of claim 5 wherein there is included a multiple number of flap layers of waterimpervious material having sealing section means at their distal ends for mating with opposing parts of the wall section(s) from which they extend, thereby providing a multitude of water-tight seals.

10. The enclosure structure of claim 1 wherein the rigid structure includes a multiple number of diverging members, said sections when joined together having a like number of apertures which are formed about the diverging members, said joining means intersecting with said apertures.

11. The enclosure structure of claim 1 wherein said sheet sections include a series of floation pockets along their upper areas to assist in properly positioning said sheet sections when they are joined together about the rigid structure.

12. The enclosure structure of claim 1 wherein said joining means also includes a series of stress belt means for positioning across the joining means for pulling said sheet sections together to take up the lateral stress in those areas.

13. The enclosure structure of claim 1 wherein there is further included an outer enclosing net of mesh material following'the general configuration of said sheet sections when joined together but defining substantially less enclosed volume than said sheet sections when joined together and when fully extended, said net being placed on the exterior of said sheet sections when joined together, thereby preventing the creation of any substantial, damaging lateral or surface stresses on said joining means.

14. The enclosure structure of claim 1 wherein said sheet sections are made of a composite material made up of an inner layer of heat and fire resistant material such as an abestos material, a film layer that is waterimpervious, a strain resistant layer, and an abrasive resistant outer layer.

15. The enclosure structure of claim 2 wherein said sealing means includes a layer of foam material placed in juxtaposition to the sheet material which forms said aperture and clamping means for clamping said sheet section and said layer of foam material tightly to the rigid structure.

16. The enclosure structure of claim 15 wherein said clamping means has on its inner work surface a series of projections to enhance and localize its clamping capabilities.

17. The enclosure structure of claim 1 wherein there is included a series of tie down line means connected to said sheet sections around said relatively large bottom opening formed when said sheel sections are joined together for tying and holding the bottom of said sheet sections down.

18. The enclosure structure of claim 1 wherein the rigid structure includes irregular sections which provide less than a completely rounded surface, the enclosure structure further including a multiple number of relatively small, inflatable filler bag means inflated to a high pressure for placing in and around the irregular surface contours for producing a generally rounded surface. 

1. An inflatable, inverted bag-like enclosure structure of flexible material for fastening about and to a rigid structure, at least a part of which is in water, to define an enclosed work space, at least a portion of which is below the water, about said rigid structure, and having an internal, gaseous environment which supports by its pressure said enclosure structure, said internal environment being different from that on the outside of said enclosure structure, said enclosure structure comprising a multiple number of separate but joinable extended sheet sections of flexible material, and joining means mounted at the edges of said sections for joining them together, said sections when joined together having at least one aperture therein, which is fitted around said rigid structure, and a relatively large bottom opening.
 2. The enclosure structure of claim 1 wherein there is further included sealing means along said aperture for at least substantially sealing said enclosure about said rigid structure.
 3. The enclosure structure of claim 1 wherein said joining means comprises a zipper structure located along the periphery of said sections.
 4. The enclosure structure of claim 3 wherein said joining means includes dual wall sections each joined together along their edges by means of zipper structures, one being a strong, heavy duty, structural type of zipper structure which can withstand high stress, and the other being a water-tight zipper structure, the later including slack portions in its wall sections, thereby avoiding any great structural stresses from being placed on said water-tight zipper structure.
 5. The enclosure structure of claim 3 wherein said joining means includes two wall sections each joined together along their edges by means of zipper structures which define between themselves an enclosed housing, one of said wall sections including a flap layer of water-impervious material extending out therefrom within said housing and having sealing section means at its distal end for mating with the opposing part of the wall section from which it extends and for forming a water-tight seal between said flap layer and said opposing part, pressure means being included within said housing for pressing said sealing section means against said opposing part.
 6. The enclosure structure of claim 5 wherein said pressure means comprises an inflatable bag.
 7. The enclosure structure of claim 5 wherein there is included a projecting, longitudinal bead on said opposing part where it mates with said sealing section means for enhancing the sealing action.
 8. The enclosure structure of claim 5 wherein said sealing section means comprises a section of low density clOsed cellular foam.
 9. The enclosure structure of claim 5 wherein there is included a multiple number of flap layers of water-impervious material having sealing section means at their distal ends for mating with opposing parts of the wall section(s) from which they extend, thereby providing a multitude of water-tight seals.
 10. The enclosure structure of claim 1 wherein the rigid structure includes a multiple number of diverging members, said sections when joined together having a like number of apertures which are formed about the diverging members, said joining means intersecting with said apertures.
 11. The enclosure structure of claim 1 wherein said sheet sections include a series of floation pockets along their upper areas to assist in properly positioning said sheet sections when they are joined together about the rigid structure.
 12. The enclosure structure of claim 1 wherein said joining means also includes a series of stress belt means for positioning across the joining means for pulling said sheet sections together to take up the lateral stress in those areas.
 13. The enclosure structure of claim 1 wherein there is further included an outer enclosing net of mesh material following the general configuration of said sheet sections when joined together but defining substantially less enclosed volume than said sheet sections when joined together and when fully extended, said net being placed on the exterior of said sheet sections when joined together, thereby preventing the creation of any substantial, damaging lateral or surface stresses on said joining means.
 14. The enclosure structure of claim 1 wherein said sheet sections are made of a composite material made up of an inner layer of heat and fire resistant material such as an abestos material, a film layer that is water-impervious, a strain resistant layer, and an abrasive resistant outer layer.
 15. The enclosure structure of claim 2 wherein said sealing means includes a layer of foam material placed in juxtaposition to the sheet material which forms said aperture and clamping means for clamping said sheet section and said layer of foam material tightly to the rigid structure.
 16. The enclosure structure of claim 15 wherein said clamping means has on its inner work surface a series of projections to enhance and localize its clamping capabilities.
 17. The enclosure structure of claim 1 wherein there is included a series of tie down line means connected to said sheet sections around said relatively large bottom opening formed when said sheel sections are joined together for tying and holding the bottom of said sheet sections down.
 18. The enclosure structure of claim 1 wherein the rigid structure includes irregular sections which provide less than a completely rounded surface, the enclosure structure further including a multiple number of relatively small, inflatable filler bag means inflated to a high pressure for placing in and around the irregular surface contours for producing a generally rounded surface. 